Hot-air furnace



(No Model.) 3 Shets-Sheet 1. J. CUNNINGHAM.

HOT AIR FURNAGB.

No. 471619. Patented June 21, 1892.

(No Model.) 3 Sheets-Sheet 2.

J. CUNNINGHAM.

HOT AIR FURNACE.

No. 477,519. Patented June 21, 1892.

(N0M0de1.) KSheets-Sheet a.

J. CUNNINGHAM. HOT AIR PURNAGB.

No. 477,519. Patented June 21., 1892.

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UNITED STATES PATENT OFFICE.

JAMES CUNNINGHAM, OF DUSHORE, PENNSYLVANIA.

HOT-AIR FU RNAC E.

SPECIFICATION forming part of Letters Patent No. 477,519, dated June 21,1892. Application filed January 9, 1892. Serial No. 417,656. (No model.)

reference being had to the accompanying drawings, and to the figures ofreference marked. thereon, which form a part of this specification.

My invention relates to heaters or furnaces of the type used for theinterior heating of dwellings and inhabitable buildings.

It is the purpose of my invention to provide an apparatus for these useshaving an improved direct and. return draft and provided with meanswhereby the temperature and draft may be easily, quickly, and accuratelyregulated.

It is my further purpose to provide the maximum heating area for theair-chambers and to utilize to the utmost degree possible all the fuelconsumed.

My invention consists to these ends in the several novel features ofconstruction and new combinations of parts hereinafter fully set forth,and then more particularly pointed out and defined in the claimsfollowing thisspect iication".

To enable others skilled in the art to understand and to make,construct, and use my invention, I will proceed to describe the same indetail, reference being had for such purpose to theaccompanyingdrawings,in which-- Figure 1 is a central vertical section,half in elevation, showing my invent-ion. Fig.2 is a section taken uponthe line 2 2, Fig. 1. Fig. 3 isatransverse section taken in thehorizontal line 3 3, Fig. 2. Fig. 4 is a transverse section in the linei 4;, Fig. 2.

In the said drawings the reference-numeral 1 denotes the case of theheater, or that portion thereof inclosed within the outer casing. Thispart of the structure may beof any suitable form, being merely subjacent to the grate 2 and fire-pot 3 and serving as an ash-box to preventthe passage of dust and ashes to the hot-air fines.

to the grate. stantially concentric with it is a hanging airof theproducts of combustion.

The fire-box 3 is inclosed by a substantially circular wall 4, thediameter thereof increasing somewhat with the extension of said wallupward to pack the coal slightly as it descends Above the fire-box andsubdrum 5,having a closed bottom which lies above the plane of the upperedge of the wall at of the fire-box, as shown in Fig. 2, thus leaving acontinuous open space for the passage From the upper edge of the wall 4a wall 6 extends horizontally outward, forming an annular bottom to adraft-space which runs around the whole structure, being inclosed by avertical circular wall 7, which rises to the open top of the drum 5. Ata point between its top and the closed lower end of the drum 5 isintroduced a horizontal partition 8, extending from the wall 7 to thevertical wall of the drum. The space inclosed beneath this horizontalwall and the parallel wall 6 is a draft-circulation chamber havingdirect communication with the fire-box on all sides.

Opening through the bottom wall 6, upon each side of a diametrical linedrawn from front to rear, is a pipe 9 of suitably large diameter, itslower end being dropped,usually,

to a point somewhat above the plane of the grate, Where it enters thetop of a curved or partly-circular draft-chamber 10, extending aroundthe rear of the heater, its two ends terminating at or near each side ofthe extension 12, which opens from the ash-box toward the front of theheater. These ends are closed, usually,-by doors or caps 13, which giveaccess to the interior to enable it to be cleansed of dust and otheraccumulating foreign matter. Between these ends and the draft-pipes 9are arranged a series of vertical pipes 14, which terminate at theirlower ends a short distance above the top of the curved draftchamberlOand open at theirnpper-ends through the top of the draft-chamberslti, sothat air may enter the lower ends of said pipes and discharge into thehot-air space above the draft-chambers 16. At ornear each end of saiddraft-chambers is a pipe 15, which opens through the top wall only, andis therefore in communication with the interior of the draft-chamber 10.These pipes extend up to and pass through the horizontal partition-wall8, opening into draft-chambers 16, (shown in Fig. 3,) which are closedbetween the wall of the drum 5 and the wall 7. Each of thesedraft-chambers is divided from the other by a vertical fore-and-aftpartition 17, extending between the inner and the outer curved walls,and directly behind the rear edge of this partition opens the draft-flue18, which leads to the chimney, the flue opening in the wall 7 lyingabout equally upon each side of the dividing-partition. Concentric withthe pipes 15 are interior smaller pipes 19, the lower ends of which maytraverse the draft-chamber 10 and open through its bottom, or else turnlaterally and open th rough" the sides of the pipes 15, as indicated bydotted lines in Fig. 2 of the drawings. The upper extremities of saidpipes in like manner extend through the upper curved draftehambers 16and open through the top thereof, as shown in Fig. 1. The air-pipes l-lextend upward and pass through the draft-chambers 16, their extremitiesopening through the top walls of said chambers. I have shown three ofthese pipes on each side, besides the pipes 9, 15, and 19; but it isevident that the number may be varied, as well as the relative diameter.

In order to prevent coal and ashes or other matter from beingaccidentally thrown into the pipes 9, and .thus accumulating in thedraft-chambers 10, I usually place a perforated screen 20 or foraminouswire diaphragm along the rear part of the fire-box between the base ofthe drum 5 and the horizontal wall 6. Through the front portion of thewall 7, diametrically opposite the draft-flue 18, is the door-opening21, havinga passagesereen 22 extending in toward the fire-box. above theinner extremity of this passage a draft-opening 23 is formed in thepartition 8,

opening may be closed or opened either wholly or in part by means of achain 25 or its equivalent passing through an opening in the circularwall 7.

Between the wall 8 and the circular wall of the drum 5 extends avertically fore-and-aft partition 26, (shown in Fig. 3,) by which theinclosed space above the partition 8, which constitutes the twodraft-chambers 16, is divided into two substantially equal parts. Thedamper 24 is provided with a slot in which this partition lies, thefunctions of the latter being to divide the products of combustionrising from the fire-box into two volumes and compel the two currents toflow on opposite sides around the drum 5 and reunite in flue 18.

Entering the curved vertical wall 7, directly beneath thedividing-partition 17, is a horizontalor nearly-horizontal pipe 27,which passes radially and inward and penetrates the vertical wall of thedrum 5 at a point a little above its base. I have shown in Figs. 2 and 3two additional pipes 28 of similar form and arrangement,0ne upon eachside of "'ta'l'" wall 6.

Just

the door. Over the outer ends of the pipes are placed screens or hoods29, which aid in gathering the air as it rises and directing it into thereceiving ends of the pipes 27 and 28, and aiding, also, in driving itthrough the latter into the interior of the drum, which is entered bythese air-currents from widely-different directions and near the bottomof the drum 5 is directly exposed to the hottest gases of combustion.

Rising from the top of the passage 12, which leads to the fire-box, is asmall draft-regulating pipe 31, the upper end of which receives anipple-joint 32, dropping from the horizon- The pipe is provided with adamper 33, by which air may be admitted to the draft-space just abovethe top of the circular wall of the fire-box. This air may be used todiminish the force of the draft or to aid in the more complete ignitionand c011- sumption of the products of combustion.

It will readily be seen that by throwing open the damper 24 the entiredraft may be allowed to pass through the draft-chamber 16, or byadjusting said damper it may be divided between the upper and the lowerdraftchambers 16 and 10, or driven wholly through the latter through thedrop-pipes 9, thence up through the pipes 15, around the exterior :ofthe pipes 19,thence through the draftchambers 16, and out through theflue.

The outside casing of the heater is usually placed just outside thehoods 20 and contracted at its lower portion to unite with the damperedbase-plate 34, which is provided with openings 35 to receive air fromthe airbox. These parts require no special description, being ofsubstantially the well-known construction. 7

Having described my invention and set forth its merits, what I claim isa damper 24 being provided by which said 1. In a heater or air-furnace,the combination, with a fire-box having a horizontal wall extendingoutward from its top and forming,

in conjunction with a vertical and an upper f horizontal wall, adraft-space surrounding I the top of the fire-box, of a curved draft- Ichamber extending nearly around the outside of the fire-box, draft-pipesconnecting the said chamber with curved draft-chambers above, i thebottom of said upper draft-chambers being the top of the draft-spacesurrounding the top of the fire-box, and drop-pipes opening from spacein rear of the top of the firebox into the top of the lower curveddraftchamber, substantially as and for the purposes set forth.

2. In a heater or furnace, the combination, with an upper and a lowercurved draft-chamber connected at the front of the heater by verticaldraft-pipes, of a draft-space extending entirely around the open top ofthe fire box, and drop-pipes giving communication between said space andthe lowerdraft-chamber air-pipes traversing said upper chamber, and thedraft-space between it and the lower curved drattchamber, and a damperregulating a draft-opening in the bottom of the upper draft-chamber, thebottom of which chamber forms the top of said draft-space, by whichdirect communication between the draft-space and said upperdraft-chamber may be established and cut off, substantially as and forthe purposes set forth.

3. In a heater or furnace, the combination, with a fire-box and with adraft-space surrounding the top thereof, of two partly-cir culardraft-chambers, one above and one below, air-pipes traversing the upperchamber and the draft-space between it and the lower draft-chamber,draft-pipes connecting the rear portion of the lower draft-chamber withthe draft-space around the top of the fire-box, vertical pipesconnecting said draft-chambers, a drum surrounded by and dropping belowthe upper draft-chamber, its closed bottom hanging above the fire-space,and radial pipes giving communication with said drum and the exterior,their outer ends having hoods or screens, and the inner ends openingabove the bottom of the drum, substantially as and for the purposes setforth.

4. In a furnace, the combination, with the fire-chamber and with acircular draft-space surrounding and lying above the upper end of thefire-chamber, of adraftchamber partly surrounding and lying whollyoutside the fire-chamber and below the draft-space, with which it isconnected near its middle portion by drop-pipes, draft-pipes connectingthe ends of said draft-chamber with semicircular draftchambers above,concentric air-pipes traversing the draft-pipes and upper draft-chamber,a flue into which the upper semicircular chambers discharge, adraft-damper closing an opening by which the circular draft-spacecommunicates with the semicircular draftchambers above, an air-drumclosed at the bottom and open above, surrounded by and dropping belowthe semicircular draft-chambers, and radial pipes traversing thecircular draft-space and communicating with the interior of the air-drumnear its base and with the exterior hot-air space, substantially as andfor the purposes set forth.

5. In a furnace or heater, the combination, with a draft-spacecommunicating directly with the fire-chamber, of an air-drum hangingpartly within said space and having its closed bottom and lower portiondirectly over the fire-chamber, semicircular draft-spaces surroundingthe upper portion of said drum and provided with dampered openingscommunicating with the draft-space below, a flue opposite the damperedopenings into which said semicircular spaces discharge, radial airpipestraversing the draft-passage around the drum and entering the drum nearits closed bottom, their outer ends being covered by hoods having adownward inclination and em pansion or flare, substantially as and forthe purposes set forth.

6. In a furnace or heater, the combination, with an air-drum having itsclosed lower portion hanging over the fire-chamber and surrounded by acircular draft-space traversed by air-heating pipes, of radialair-heating pipes connecting the interior of said drum with the exteriorhot-air space, the exterior ends of said pipes being overhung by hoodsopening downward and converging toward the pipe-entrance, substantiallyas and for the purposes set forth.

In testimony whereof I affix my signature in presence of two witnesses.

JAMES CUNNINGHAM.

Witnesses:

Row J. THOMSON, F. V. THOMSON.

